Reading The Absolute Position With Communication - Delta ASDA-A3 Series User Manual

ASDA-A3

10.3.5.2 Reading the absolute position with communication

You can access the data of the absolute encoder through two communication methods: instant
access or register access.
Instant access
Instant access refers to reading the motor's feedback position as soon as power is supplied to
the servo. When you set the status monitoring register 1 to the motor's feedback pulse number
(P0.017 = 0), you can access the motor's current position by reading P0.009.
Register access
Register access means the motor's position is temporarily stored in the register and the read
value does not change with the motor's movement. Once you set P0.049 with communication,
the encoder status and motor absolute position (number of revolutions), and pulse number (or
PUU) are stored in P0.050, P0.051, and P0.052 respectively. You can set to read the value in
the unit of pulse or PUU with P2.070 [Bit 1].
◼ When P0.049 is set to 1, the drive does not clear the position error when reading the position
value.
◼ When P0.049 is set to 2, the drive clears the position error at the same time when reading
the position value. After the motor is enabled, it moves slightly forward and backward to
correct its position even it is stopped. To avoid the difference between the actual and read
motor positions, set P0.049 to 2 to have the motor's actual position updated to the servo
drive, which clears the position error.
For example, the motor's current position is 20000, but it varies between 19999 and 20001.
If you send the command to read the motor's position when it stops at 20001, the read value
is 20001. Meanwhile, 20001 is updated to the servo drive, meaning the position error is
cleared. If the servo drive does not update the read position, a command error occurs.
Absolute System
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